[nes] timing and accuracy work.

BizHawk.Emulation/BizHawk.Emulation.csproj

@@ -224,6 +224,7 @@
     <Compile Include="Sound\Utilities\Waves.cs" />
   </ItemGroup>
   <ItemGroup>
+    <Content Include="Consoles\Nintendo\Docs\test_status.txt" />
     <Content Include="Consoles\PC Engine\Compat.txt" />
     <Content Include="Consoles\Sega\SMS\Compat.txt" />
     <Content Include="Notes.txt" />

BizHawk.Emulation/CPUs/MOS 6502/Execute.cs

@@ -24,9 +24,20 @@ namespace BizHawk.Emulation.CPUs.M6502
                 }
                 if (IRQ && !FlagI)
                 {
+                    if (SEI_Pending)
+                        FlagI = true;
                     TriggerException(ExceptionType.IRQ);
                 }
-
+                if (CLI_Pending)
+                {
+                    FlagI = false;
+                    CLI_Pending = false;
+                }
+                if (SEI_Pending)
+                {
+                    FlagI = true;
+                    SEI_Pending = false;
+                }
                 if(debug) Console.WriteLine(State());
 
                 ushort this_pc = PC;
@@ -209,7 +220,15 @@ TriggerException(ExceptionType.BRK);
                         PendingCycles -= 5; TotalExecutedCycles += 5;
                         break;
                     case 0x28: // PLP
-                        P = ReadMemory((ushort)(++S + 0x100));
+                        //handle I flag differently. sort of a sloppy way to do the job, but it does finish it off.
+                        value8 = ReadMemory((ushort)(++S + 0x100));
+                        if ((value8 & 0x04) != 0 && !FlagI)
+                        	SEI_Pending = true;
+                        if ((value8 & 0x04) == 0 && FlagI)
+                        	CLI_Pending = true;
+                        value8 &= unchecked((byte)~0x04);
+                        P &= 0x04;
+                        P |= value8;
 FlagT = true;//this seems wrong
                         PendingCycles -= 4; TotalExecutedCycles += 4;
                         break;
@@ -431,7 +450,8 @@ FlagT = true;// this seems wrong
                         PendingCycles -= 6; TotalExecutedCycles += 6;
                         break;
                     case 0x58: // CLI
-                        FlagI = false;
+                        //FlagI = false;
+                        CLI_Pending = true;
                         PendingCycles -= 2; TotalExecutedCycles += 2;
                         break;
                     case 0x59: // EOR addr,Y
@@ -594,7 +614,8 @@ FlagT = true;// this seems wrong
                         PendingCycles -= 6; TotalExecutedCycles += 6;
                         break;
                     case 0x78: // SEI
-                        FlagI = true;
+                        //FlagI = true;
+                        SEI_Pending = true;
                         PendingCycles -= 2; TotalExecutedCycles += 2;
                         break;
                     case 0x79: // ADC addr,Y

BizHawk.Emulation/CPUs/MOS 6502/MOS6502.cs

@@ -103,6 +103,9 @@ namespace BizHawk.Emulation.CPUs.M6502
 
         public bool IRQ;
         public bool NMI;
+		public bool CLI_Pending;
+		public bool SEI_Pending;
+		public bool EscapeRequest;
 
 		public void SyncState(Serializer ser)
 		{

BizHawk.Emulation/Consoles/Nintendo/Docs/test_status.txt

@@ -0,0 +1,32 @@
+look for tests here: http://wiki.nesdev.com/w/index.php/Emulator_tests
+
+blargg's MMC3: 
+	FAIL for 4 and 6. i think 4 might not fail until some invisible PPU operations are correct. neither nintendulator or fceux pass these.
+
+blargg's ppu tests: 
+	PASS for all but power_up_palette.nes which is lame
+
+blargg's ppu_vbl_nmi:
+	FAIL for 9. But hardly anyone passes this.....
+	
+blargg's sprite hit tests:
+	FAIL for 9 and 10. fceux passes 10 (oldppu) and nintendulator passes both. 
+	boath are not going to work any time soon due to sprite pattern decoding being separate from BG pattern fetching instead of interleaved.
+	
+all_instrs.nes
+	FAIL (freezes emu??). I think this requires undocumented instructions.
+	
+cpu_interrupts.nes
+	PASS
+	
+instr_misc.nes
+	PASS
+	
+instr_timing.nes
+	PASS
+	
+nestest.nes
+	PASS
+	
+official_only.nes
+	PASS

BizHawk.Emulation/Consoles/Nintendo/NES/BoardSystem.cs

@@ -15,6 +15,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			bool Configure(NES.EDetectionOrigin origin);
 			byte ReadPRG(int addr);
 			byte ReadPPU(int addr); byte PeekPPU(int addr);
+			void AddressPPU(int addr);
 			byte ReadWRAM(int addr);
 			byte ReadEXP(int addr);
 			void WritePRG(int addr, byte value);
@@ -140,6 +141,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				}
 			}
 
+			public virtual void AddressPPU(int addr) { }
 			public virtual byte PeekPPU(int addr) { return ReadPPU(addr); }
 
 			public virtual byte ReadPPU(int addr)

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/AxROM.cs

@@ -63,7 +63,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		public override void WritePRG(int addr, byte value)
 		{
 			if (ROM != null && bus_conflict) value = HandleNormalPRGConflict(addr,value);
-			prg = (value*2) & prg_mask;
+			int prg_bank = value & 7;
+			prg = (prg_bank * 2) & prg_mask;
 			if ((value & 0x10) == 0)
 				SetMirrorType(NES.NESBoardBase.EMirrorType.OneScreenA);
 			else

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/MMC3_family.cs

@@ -22,6 +22,13 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		{
 			bank_regs[8] = (byte)(num_prg_banks - 1);
 			bank_regs[9] = (byte)(num_prg_banks - 2);
+			bank_regs[0] = 0;
+			bank_regs[1] = 1;
+			bank_regs[2] = 2;
+			bank_regs[3] = 3;
+			bank_regs[4] = 4;
+			bank_regs[5] = 5;
+			sync_2k_chr();
 		}
 
 		public void Dispose()
@@ -34,10 +41,28 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		public int chr_mode, prg_mode, reg_addr;
 
 		//this contains the 8 programmable regs and 2 more at the end to represent PRG banks -2 and -1; and 4 more at the end to break down chr regs 0 and 1
+		//in other words:
+		//0: chr reg 0 (not used directly)
+		//1: chr reg 1 (not used directly)
+		//2,3,4,5: chr reg 2,3,4,5
+		//6,7: prg reg 6,7
+		//8,9: prg reg -2,-1
+		//10: chr reg 0A
+		//11: chr reg 0B
+		//12: chr reg 1A
+		//13: chr reg 1B
 		ByteBuffer bank_regs = new ByteBuffer(14);
 		ByteBuffer prg_lookup = new ByteBuffer(new byte[] { 6, 7, 9, 8, 9, 7, 6, 8 });
 		ByteBuffer chr_lookup = new ByteBuffer(new byte[] { 10, 11, 12, 13, 2, 3, 4, 5 });
 
+		void sync_2k_chr()
+		{
+			bank_regs[10] = (byte)((bank_regs[0] & ~1) + 0);
+			bank_regs[11] = (byte)((bank_regs[0] & ~1) + 1);
+			bank_regs[12] = (byte)((bank_regs[1] & ~1) + 0);
+			bank_regs[13] = (byte)((bank_regs[1] & ~1) + 1);
+		}
+
 		public virtual void WritePRG(int addr, byte value)
 		{
 			switch (addr & 0x6001)
@@ -49,11 +74,7 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					break;
 				case 0x0001: //$8001
 					bank_regs[reg_addr] = value;
-					//setup the 2K chr regs
+					sync_2k_chr();
-					bank_regs[10] = (byte)((bank_regs[0] & ~1) + 0);
-					bank_regs[11] = (byte)((bank_regs[0] & ~1) + 1);
-					bank_regs[12] = (byte)((bank_regs[1] & ~1) + 0);
-					bank_regs[13] = (byte)((bank_regs[1] & ~1) + 1);
 					break;
 			}
 		}
@@ -114,37 +135,49 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				case 0x2001: //$A001
 					//wram enable/protect
 					break;
-				case 0x4000: //$C000
+				case 0x4000: //$C000 - IRQ Reload value
 					irq_reload = value;
 					break;
-				case 0x4001: //$C001
+				case 0x4001: //$C001 - IRQ Clear
 					irq_counter = 0;
 					break;
-				case 0x6000: //$E000
+				case 0x6000: //$E000 - IRQ Acknowledge / Disable
 					irq_enable = false;
 					irq_pending = false;
 					SyncIRQ();
 					break;
-				case 0x6001: //$E001
+				case 0x6001: //$E001 - IRQ Enable
 					irq_enable = true;
 					SyncIRQ();
 					break;
 			}
 		}
 
+		void IRQ_EQ_Pass()
+		{
+			if (irq_enable)
+				irq_pending = true;
+			SyncIRQ();
+		}
+
 		void ClockIRQ()
 		{
 			if (irq_counter == 0)
+			{
 				irq_counter = irq_reload;
+
+				//TODO - MMC3 variant behaviour??? not sure
+				//was needed to pass 2-details.nes
+				if (irq_counter == 0)
+					IRQ_EQ_Pass();
+			}
 			else
 			{
 				irq_counter--;
 				//Console.WriteLine(irq_counter);
 				if (irq_counter == 0)
 				{
-					if (irq_enable)
+					IRQ_EQ_Pass();
-						irq_pending = true;
-					SyncIRQ();
 				}
 			}
 		}
@@ -241,21 +274,9 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 		//state
 		protected MMC3 mmc3;
 
-		public override byte ReadPPU(int addr)
+		public override void AddressPPU(int addr)
 		{
 			mmc3.Tick_PPU(addr);
-			return base.ReadPPU(addr);
-		}
-
-		public override void WritePPU(int addr, byte value)
-		{
-			mmc3.Tick_PPU(addr);
-			base.WritePPU(addr, value);
-		}
-
-		public override void WritePRG(int addr, byte value)
-		{
-			base.WritePRG(addr, value);
 		}
 		
 		protected override void BaseSetup()

BizHawk.Emulation/Consoles/Nintendo/NES/Boards/MMC3_family/TxROM.cs

@@ -50,6 +50,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			//analyze board type
 			switch (Cart.board_type)
 			{
+				case "TXROM-HOMEBREW":
+					break;
 				case "NES-TBROM": //tecmo world cup soccer (DE) [untested]
 					AssertPrg(64); AssertChr(64); AssertVram(0); AssertWram(0);
 					AssertBattery(false);

BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs

@@ -96,13 +96,22 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			else
 				cycles <<= 4;
 
+
+			//tricky logic to try to run one instruction at a time
 			cpu_accumulate += cycles;
-			if (cpu_accumulate >= 48)
+			int cpu_cycles = cpu_accumulate / 48;
+			for (; ; )
 			{
-				int todo = cpu_accumulate / 48;
+				if (cpu_cycles == 0) break;
-				cpu_accumulate -= todo * 48;
+				int need_cpu = -cpu.PendingCycles + 1;
+				if (cpu_cycles < need_cpu) break;
+				if (need_cpu == 0) need_cpu = 1;
+				int todo = need_cpu;
+				cpu_cycles -= todo;
+				cpu_accumulate -= 48*todo;
 				cpu.Execute(todo);
 				apu.Run(todo);
+				ppu.TickCpu();
 			}
 		}
 

BizHawk.Emulation/Consoles/Nintendo/NES/PPU.cs

@@ -18,12 +18,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
             //when the ppu issues a write it goes through here and into the game board
 			public void ppubus_write(int addr, byte value)
 			{
+				nes.board.AddressPPU(addr);
 				nes.board.WritePPU(addr, value);
 			}
 
 			//when the ppu issues a read it goes through here and into the game board
 			public byte ppubus_read(int addr)
 			{
+				nes.board.AddressPPU(addr);
 				//apply freeze
                 if (ppubus_freeze[addr].IsFrozen)
                     return ppubus_freeze[addr].value;
@@ -89,17 +91,48 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				nes.cpu.NMI = true;
 			}
 
+			public void TickCpu()
+			{
+				if (NMI_PendingCycles > 0)
+				{
+					NMI_PendingCycles--;
+					if (NMI_PendingCycles == 0)
+					{
+						TriggerNMI();
+					}
+				}
+			}
+
 			void runppu(int x)
 			{
 				//pputime+=x;
 
 				//DON'T LIKE THIS....
 				ppur.status.cycle += x;
-				if (ppur.status.cycle > ppur.status.end_cycle)
+				while(ppur.status.cycle >= ppur.status.end_cycle)
 					ppur.status.cycle -= ppur.status.end_cycle;
 
+				if(x == 0) return;
+
+				nes.RunCpu(1);
+				x--;
+
+				if (Reg2002_vblank_active_pending)
+				{
+					if (Reg2002_vblank_active_pending)
+						Reg2002_vblank_active = 1;
+					Reg2002_vblank_active_pending = false;
+				}
+
+				if (Reg2002_vblank_clear_pending)
+				{
+					Reg2002_vblank_active = 0;
+					Reg2002_vblank_clear_pending = false;
+				}
+
+				
+				if (x == 0) return;
 				nes.RunCpu(x);
-				//pputime -= cputodo<<2;
 			}
 
 			//hack

BizHawk.Emulation/Consoles/Nintendo/NES/PPU.regs.cs

@@ -294,6 +294,9 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			Bit Reg2002_objoverflow;  //Sprite overflow. The PPU can handle only eight sprites on one scanline and sets this bit if it starts drawing sprites.
 			Bit Reg2002_objhit; //Sprite 0 overlap.  Set when a nonzero pixel of sprite 0 is drawn overlapping a nonzero background pixel.  Used for raster timing.
 			Bit Reg2002_vblank_active;  //Vertical blank start (0: has not started; 1: has started)
+			bool Reg2002_vblank_active_pending; //set of Reg2002_vblank_active is pending
+			bool Reg2002_vblank_clear_pending; //ppu's clear of vblank flag is pending
+			int NMI_PendingCycles;
 			byte PPUGenLatch;
 			public PPUREGS ppur;
 			Reg_2000 reg_2000;
@@ -324,11 +327,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			//PPU CONTROL (write)
 			void write_2000(byte value)
 			{
-				if (!reg_2000.vblank_nmi_gen & ((value & 0x80) != 0) && (Reg2002_vblank_active))
+				if (!reg_2000.vblank_nmi_gen & ((value & 0x80) != 0) && (Reg2002_vblank_active) && !Reg2002_vblank_clear_pending)
 				{
 					//if we just unleashed the vblank interrupt then activate it now
-					//FCEUX would use a "trigger NMI2" here in order to result in some delay effect
+					NMI_PendingCycles = 2;
-					TriggerNMI();
 				}
 				reg_2000.Value = value;
 			}
@@ -354,12 +356,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				int ret = (Reg2002_vblank_active << 7) | (Reg2002_objhit << 6) | (Reg2002_objoverflow << 5) | (PPUGenLatch & 0x1F);
 
 				Reg2002_vblank_active = 0;
+				Reg2002_vblank_active_pending = false;
 
 				return (byte)ret;
 			}
 			void clear_2002()
 			{
-				Reg2002_vblank_active = Reg2002_objhit = Reg2002_objoverflow = 0;
+				Reg2002_objhit = Reg2002_objoverflow = 0;
+				Reg2002_vblank_clear_pending = true;
 			}
 
 			//OAM ADDRESS (write)
@@ -378,7 +382,9 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				OAM[reg_2003] = value;
 				reg_2003++;
 			}
-			byte read_2004() { return 0xFF; /* TODO !!!!!! THIS IS UGLY. WE SHOULD PASTE IT IN OR REWRITE IT BUT WE NEED TO ASK QEED FOR TEST CASES*/ }
+			byte read_2004() {
+				return OAM[reg_2003];
+			}
 
 			//SCROLL (write)
 			void write_2005(byte value)
@@ -414,6 +420,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					ppur._vt |= (value >> 5);
 					ppur._ht = value & 31;
 					ppur.install_latches();
+
+					nes.board.AddressPPU(ppur.get_2007access());
 				}
 				vtoggle ^= true;
 			}
@@ -443,6 +451,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 				}
 
 				ppur.increment2007(reg_2000.vram_incr32 != 0);
+				int newaddr = ppur.get_2007access() & 0x3FFF;
+				nes.board.AddressPPU(newaddr);
 			}
 			byte read_2007()
 			{
@@ -463,6 +473,9 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 				ppur.increment2007(reg_2000.vram_incr32 != 0);
 				
+				int newaddr = ppur.get_2007access() & 0x3FFF;
+				nes.board.AddressPPU(newaddr);
+
 				return ret;
 			}
 			//--------

BizHawk.Emulation/Consoles/Nintendo/NES/PPU.run.cs

@@ -1,5 +1,7 @@
 //http://nesdev.parodius.com/bbs/viewtopic.php?p=4571&sid=db4c7e35316cc5d734606dd02f11dccb
 
+//todo - read http://wiki.nesdev.com/w/index.php/PPU_sprite_priority
+
 using System;
 using System.Diagnostics;
 using System.Globalization;
@@ -85,17 +87,19 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					return;
 				}
 
-				Reg2002_vblank_active = 1;
+				Reg2002_vblank_active_pending = true;
 				ppuphase = PPUPHASE.VBL;
 
-				//Not sure if this is correct.  According to Matt Conte and my own tests, it is.
+				//Not sure if this is correct.  According to Matt Conte and my own tests, it is. Timing is probably off, though.
-				//Timing is probably off, though.
 				//NOTE:  Not having this here breaks a Super Donkey Kong game.
 				reg_2003 = 0;
-				const int delay = 20; //fceu used 12 here but I couldnt get it to work in marble madness and pirates.
 
-				runppu(delay); //X6502_Run(12);
+				//fceu/fceux had 12 here, but 15 was required to pass blargg's 05-nmi_timing.nes
-				if (reg_2000.vblank_nmi_gen) TriggerNMI();
+				const int delay = 15;
+				runppu(3);
+				bool nmi_destiny = reg_2000.vblank_nmi_gen && Reg2002_vblank_active;
+				runppu(delay - 3);
+				if (nmi_destiny) TriggerNMI();
 				if (PAL)
 					runppu(70 * (kLineTime) - delay);
 				else
@@ -103,17 +107,6 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 				//this seems to run just before the dummy scanline begins
 				clear_2002();
-				//this early out caused metroid to fail to boot. I am leaving it here as a reminder of what not to do
-				//if(!PPUON) { runppu(kLineTime*242); goto finish; }
-
-				//There are 2 conditions that update all 5 PPU scroll counters with the
-				//contents of the latches adjacent to them. The first is after a write to
-				//2006/2. The second, is at the beginning of scanline 20, when the PPU starts
-				//rendering data for the first time in a frame (this update won't happen if
-				//all rendering is disabled via 2001.3 and 2001.4).
-
-				//if(PPUON)
-				//	ppur.install_latches();
 
 				TempOAM* oams = stackalloc TempOAM[128];
 				int* oamcounts = stackalloc int[2];
@@ -142,6 +135,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					//two of those tiles were read in the last scanline.
 					for (int xt = 0; xt < 32; xt++)
 					{
+						if (sl == 31 && xt == 31)
+						{
+							int zzz = 9;
+						}
 						Read_bgdata(ref bgdata[xt + 2]);
 
 						//ok, we're also going to draw here.
@@ -205,11 +202,16 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 											//transparent pixel bailout
 											if (spixel == 0) continue;
 
+											//TODO - make sure we dont trigger spritehit if the edges are masked for either BG or OBJ
 											//spritehit:
 											//1. is it sprite#0?
 											//2. is the bg pixel nonzero?
 											//then, it is spritehit.
-											if (oam->index == 0 && (pixel & 3) != 0 && rasterpos < 255)
+											if (oam->index == 0)
+											{
+												int zzz = 9;
+											}
+											if (oam->index == 0 && pixel != 0 && rasterpos < 255)
 											{
 												Reg2002_objhit = true;
 											}
@@ -397,20 +399,16 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 
 					ppuphase = PPUPHASE.BG;
 
-					//fetch BG: two tiles for next line
-					for (int xt = 0; xt < 2; xt++)
-						Read_bgdata(ref bgdata[xt]);
-
 					//I'm unclear of the reason why this particular access to memory is made.
 					//The nametable address that is accessed 2 times in a row here, is also the
 					//same nametable address that points to the 3rd tile to be rendered on the
 					//screen (or basically, the first nametable address that will be accessed when
 					//the PPU is fetching background data on the next scanline).
 					//(not implemented yet)
-					runppu(kFetchTime*2);
+					runppu(kFetchTime * 2);
 					if (sl == 0)
 					{
-						if (idleSynch && reg_2001.PPUON && !PAL)
+						if (idleSynch && reg_2001.show_bg && !PAL)
 							ppur.status.end_cycle = 340;
 						else
 							ppur.status.end_cycle = 341;
@@ -418,7 +416,10 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 					}
 					else
 						ppur.status.end_cycle = 341;
-					//runppu(kFetchTime);
+
+					//fetch BG: two tiles for next line
+					for (int xt = 0; xt < 2; xt++)
+						Read_bgdata(ref bgdata[xt]);
 
 					//After memory access 170, the PPU simply rests for 4 cycles (or the
 					//equivelant of half a memory access cycle) before repeating the whole

BizHawk.Emulation/Consoles/Nintendo/NES/iNES.cs

@@ -55,12 +55,16 @@ static string ClassifyTable = @"
 1	32	32	8	0	NES-SEROM; lolo
 1	128	0	8	0	NES-SNROM; zelda
 1	128	128	8	0	NES-SKROM; zelda 2
-1	128	0	8	8	NES-SNROM; some of blargg's tests (apu)
+1	32	0	8	8	NROM-HOMEBREW; instr_timing.nes
-1	256	0	8	8	NES-SNROM; some of blargg's test (cpu tests)
+1	64	0	8	8	NROM-HOMEBREW; instr_misc.nes
+1	80	0	8	8	NROM-HOMEBREW; blargg's cpu_interrupts.nes
+1	128	0	8	8	NES-SNROM; some of blargg's tests (apu) [TODO recheck as NROM-HOMEBREW]
+1	256	0	8	8	NES-SNROM; some of blargg's test (cpu tests) [TODO recheck as NROM-HOMEBREW]
 2	128	0	8	0	NES-UNROM; mega man
 2	256	0	8	0	NES-UOROM; paperboy 2
 3	32	32	8	0	NES-CNROM; adventure island
 4	128	128	8	0	NES-TSROM; double dragon 2 (should be TL1ROM but maybe this will work)
+4	32	8	8	0	TXROM-HOMEBREW; blargg's mmc3 tests
 7	128	0	8	0	NES-ANROM; marble madness
 7	256	0	8	8	NES-AOROM; battletoads
 11	32	16	8	0	Discrete_74x377

CpuCoreGenerator/MOS 6502/CoreGenerator.cs

@@ -362,7 +362,6 @@ namespace M6502
             w.WriteLine("            PendingCycles += cycles;");
             w.WriteLine("            while (PendingCycles > 0)");
             w.WriteLine("            {");
-
             w.WriteLine("                if (NMI)");
             w.WriteLine("                {");
             w.WriteLine("                    TriggerException(ExceptionType.NMI);");
@@ -370,9 +369,20 @@ namespace M6502
             w.WriteLine("                }");
             w.WriteLine("                if (IRQ && !FlagI)");
             w.WriteLine("                {");
+            w.WriteLine("                    if (SEI_Pending)");
+            w.WriteLine("                        FlagI = true;");
             w.WriteLine("                    TriggerException(ExceptionType.IRQ);");
             w.WriteLine("                }");
-            w.WriteLine("");
+            w.WriteLine("                if (CLI_Pending)");
+            w.WriteLine("                {");
+            w.WriteLine("                    FlagI = false;");
+            w.WriteLine("                    CLI_Pending = false;");
+            w.WriteLine("                }");
+            w.WriteLine("                if (SEI_Pending)");
+            w.WriteLine("                {");
+            w.WriteLine("                    FlagI = true;");
+            w.WriteLine("                    SEI_Pending = false;");
+            w.WriteLine("                }");
 
             w.WriteLine("                if(debug) Console.WriteLine(State());");
             w.WriteLine("");

CpuCoreGenerator/MOS 6502/Instructions.cs

@@ -82,7 +82,8 @@ namespace M6502
 
         private void CLI(OpcodeInfo op, TextWriter w)
         {
-            w.WriteLine(Spaces + "FlagI = false;");
+            w.WriteLine(Spaces + "//FlagI = false;");
+            w.WriteLine(Spaces + "CLI_Pending = true;");
             w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
         }
 
@@ -244,7 +245,15 @@ namespace M6502
 
         private void PLP(OpcodeInfo op, TextWriter w)
         {
-            w.WriteLine(Spaces + "P = ReadMemory((ushort)(++S + 0x100));");
+            w.WriteLine(Spaces + "//handle I flag differently. sort of a sloppy way to do the job, but it does finish it off.");
+            w.WriteLine(Spaces + "value8 = ReadMemory((ushort)(++S + 0x100));");
+            w.WriteLine(Spaces + "if ((value8 & 0x04) != 0 && !FlagI)");
+            w.WriteLine(Spaces + "\tSEI_Pending = true;");
+            w.WriteLine(Spaces + "if ((value8 & 0x04) == 0 && FlagI)");
+            w.WriteLine(Spaces + "\tCLI_Pending = true;");
+            w.WriteLine(Spaces + "value8 &= unchecked((byte)~0x04);");
+            w.WriteLine(Spaces + "P &= 0x04;");
+            w.WriteLine(Spaces + "P |= value8;");
 w.WriteLine("FlagT = true;//this seems wrong");//this seems wrong
             w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
         }
@@ -333,7 +342,8 @@ w.WriteLine("FlagT = true;// this seems wrong");//this seems wrong
 
         private void SEI(OpcodeInfo op, TextWriter w)
         {
-            w.WriteLine(Spaces + "FlagI = true;");
+            w.WriteLine(Spaces + "//FlagI = true;");
+            w.WriteLine(Spaces + "SEI_Pending = true;");
             w.WriteLine(Spaces + "PendingCycles -= {0}; TotalExecutedCycles += {0};", op.Cycles);
         }